At the height of the English Civil War, scholar Hubert Leyton, a man of peace who has so far avoided involvement in the conflict, is asked for help by the desperate people of Marsham. His cousin, the Earl of Deeping, having found himself on the losing side at the Battle of Naseby, has retreated with a villainous crew of soldiers and mercenaries to his island castle of Deeping Hold, and is demanding supplies the people of Marsham can't provide...